PR-20 Denial Code: Injury or Illness Covered by the Liability Carrier

PR-20 is Claim Adjustment Reason Code 20 with group code PR. CARC 20 means this injury or illness is covered by the liability carrier. A liability carrier is the insurer of someone who may be to blame for the injury, such as a driver at fault in a crash. The payer thinks that insurer should pay first. It put the amount under patient responsibility. Many people search for “pr 20 denial code”, and that is the phrase this page answers. (Primary sources: X12 Claim Adjustment Reason Codes · CMS Claims Processing Manual, Ch. 22, §60.1 · CMS Medicare Secondary Payer Manual, Ch. 3)

Quick answer: PR-20 is a who-pays-first problem, not a coding error. Ask the patient if someone else caused the injury. If so, get the carrier name, the claim number and the date of injury, then bill that carrier. If not, send the payer the facts so it can reprocess the claim. Do not treat the patient as the only payer yet.

Part of our denial codes library. Written by Manikandan, a revenue cycle management specialist with more than 10 years of US medical billing experience. Last reviewed: 16 October 2026. Official code wording is quoted word for word from X12; Medicare rules link to their CMS source.

PR-20 denial code description (official X12 wording)

X12 Claim Adjustment Reason Code 20, verbatim:

“This injury/illness is covered by the liability carrier.”

Source: X12 Claim Adjustment Reason Codes, checked 16 October 2026. Start: 01/01/1995. Last Modified: 09/30/2007.

The CARC is 20. Here the group code is PR. CMS describes PR as the group code used “when the adjustment represent an amount that may be billed to the patient or insured.” CMS Transmittal 470 (2005) lists CARC 20 with group code CO, not PR, for Medicare fiscal intermediaries.

What PR-20 means in plain English

• The payer thinks another party’s insurance should pay. The injury or illness may have been caused by someone else.
• The group is PR. The remit says the patient may be responsible for the amount.
• That does not settle who pays. The liability carrier may still owe it.
• The payer needs facts. It may have seen an accident flag on this claim or an earlier one.
• Your next job is information. You need the accident facts and the carrier details.

PR-20 vs CO-19, CO-21, CO-22 and lookalikes

Code	Official X12 idea	What it tells you
PR-20	Injury/illness covered by the liability carrier	Liability insurance, patient group. This page
19	Work-related injury/illness, liability of the workers’ compensation carrier	Workers’ comp. See CO-19
21	Injury/illness is the liability of the no-fault carrier	No-fault or auto med-pay
22	Care may be covered by another payer per coordination of benefits	Other health plan. See CO-22 and PR-22
23	Payment adjusted because charges have been paid by another payer	Prior payer paid. See OA-23

How liability insurance reaches a claim

Liability insurance pays for harm that another party caused. CMS Medicare Secondary Payer Manual Ch. 3, §20.1 says providers must ask about injuries from a car crash or “other incident.” CMS adds that this “includes an incident that occurs on the provider’s premises.” The provider then records the name, address and policy number of any liability insurer.

On the CMS-1500, Items 10a through 10c ask whether employment, auto liability, or other accident involvement applies. CMS says any item checked “YES” “indicates there may be other insurance primary to Medicare.” A payer that sees an accident flag may apply CARC 20.

Common triggers for PR-20

1. Accident box checked. An auto or other accident indicator was set on this claim or on an earlier claim.
2. A known liability claim. The patient told the payer that someone else is at fault.
3. A claim-history match. For example, an earlier visit for the same injury carried accident details.
4. Wrong accident indicator. Registration set it by mistake.
5. No liability claim exists. The patient was hurt in an accident but never filed a claim against anyone.

Where PR-20 shows up in the 835

CLP*PCN90337*4*480.00*0.00*480.00*12*CLAIM227706~
SVC*HC:99284*480.00*0.00**1~
DTM*472*20260918~
CAS*PR*20*480.00~

• Status code 4 means the claim was denied.
• The line paid $0.
• CAS*PR*20*480.00 put the full charge under patient responsibility.
• The DTM line shows the service date the payer read.
• This sample is illustrative only. Real remits vary.

How to fix PR-20: decision path

1. Confirm the CAS segment. Check the group (PR), the reason (20), and the amount. Save the remit.
2. Check the claim. Look at the accident indicators, the date of injury, and the diagnosis codes.
3. Ask the patient. Was the condition caused by an accident or by another party?
4. If yes, collect the details. CMS lists the name and address of the insurance carrier, the policy or claim number, and the date of illness or injury.
5. Bill the liability carrier with those details, or send the carrier information to the health plan, depending on the plan’s process.
6. If no, tell the payer. Correct the accident fields, and send a corrected claim or a reprocessing request.
7. Check what the patient owes. Ask the payer what the PR amount is before you send a statement.
8. Keep records. Note who you called, when, and what the carrier said.

Medicare, commercial and Medicaid notes

Medicare. Medicare is not first in line when liability insurance should pay. CMS MSP Manual Ch. 3, §10.2 says Medicare does not pay “to the extent that payment has been made, or can reasonably be expected to be made.” Medicare “may make conditional payments, subject to reimbursement.” That applies when the liability insurer has not paid or will not pay promptly.

Under §30.2.1.2, a provider “may bill Medicare conditionally” when a liability claim is pending. The model questions in §20.2.1 add that liability insurance “is the primary payer only for services related to the liability settlement, judgment, or award.”

Commercial. Plans have their own accident forms. Ask the payer which form it needs, and how long you have to return it.

Medicaid. Each state has its own rules for other insurers. Check the state provider manual.

Worked example (illustrative)

A patient visits an emergency department on 18 September 2026 after a crash. The practice bills 99284. The remit shows CAS*PR*20*480.00.

Reading it: The payer believes a liability carrier is responsible for this injury.

Check: The patient says the other driver ran a red light. The patient gives the other driver’s insurer, a claim number, and the date of the crash.

Action: The biller records the carrier name, address, claim number and date of injury from CMS’s list. The biller bills the liability carrier and sends the same details to the health plan. The biller does not send a patient statement yet.

Second scenario: The patient says the injury happened alone at home and no one else was involved. The biller corrects the accident fields and sends a corrected claim, with a note for the payer.

Prevention checklist

• [ ] Ask every injury patient whether another party may be responsible.
• [ ] Record the carrier name, claim number and date of injury at registration.
• [ ] Set the accident indicators on the claim from the patient’s answers.
• [ ] Follow up on open liability claims on a set schedule.
• [ ] Track PR-20 by payer to find forms and processes that work.
• [ ] Keep the CARC and RARC guide handy for staff training.

Related denial codes

• CO-19: work-related injury, workers’ compensation carrier.
• CO-22: care may be covered by another payer per coordination of benefits.
• PR-22: the same coordination reason under patient responsibility.
• OA-23: charges paid by another payer.
• CARC and RARC guide.

Key takeaways

PR-20 says a liability carrier may owe this bill. Ask about the accident, get the carrier details, and bill the right party. If there is no liability claim, fix the claim and tell the payer.

FAQ

Quick facts

Item	Value
X12 code	20
X12 start	01/01/1995
Last modified	09/30/2007
Official wording	This injury/illness is covered by the liability carrier
Group on this page	PR
CMS 2005 group for CARC 20	CO
Common confusions	CO-19 (workers’ comp), CARC 21 (no-fault), PR-22 (coordination of benefits)
Last reviewed	16 October 2026

Sources

• X12, Claim Adjustment Reason Codes (CARC 19, 20, 21, 22, 23). CARC 20 Start 01/01/1995; Last Modified 09/30/2007. Accessed 16 Oct 2026.
• CMS, Medicare Claims Processing Manual (IOM 100-04), Ch. 22, §60.1 Group Codes. Accessed 16 Oct 2026.
• CMS, Medicare Secondary Payer Manual (IOM 100-05), Ch. 3, §10.2, §20.1, §20.2.1 and §30.2.1.2. Accessed 16 Oct 2026.
• CMS, Medicare Claims Processing Manual (IOM 100-04), Ch. 26, Items 10a through 10c. Accessed 16 Oct 2026.
• CMS, Transmittal 470 (4 Feb 2005). Accessed 16 Oct 2026.

Code wording and Medicare rules on this page were checked on 16 October 2026 against X12 and CMS sources.

Last reviewed: 16 October 2026 · This page is educational and doesn’t replace payer-specific contracts or coding rules.